Spread refried beans on one-half of the tortilla and sour cream on the other. Cover entire thing with cheese. Fold over and heat in non-stick skillet, lightly browning both sides till cheese is melted.

Also - you can line a baking sheet with foil, spray lightly with cooking spray, and "bake" the quesadillas @ 350 for about 8-10 min, until cheese is melted.